Please use caution in following this BAD ADVICE.
These laws are referred to as one-party consent statutes, and as long as you are a party to the conversation, it is legal for you to record it. (Nevada also has a one-party consent statute, but the state Supreme Court has interpreted it as an all-party rule.)
Twelve states require, under most circumstances, the consent of all parties to a conversation. Those jurisdictions are California, Connecticut, Florida, Illinois, Maryland, Massachusetts, Michigan, Montana, Nevada, New Hampshire, Pennsylvania and Washington. Be aware that you will sometimes hear these referred to inaccurately as two-party consent laws. If there are more than two people involved in the conversation, all must consent to the taping.
Regardless of the state, it is almost always illegal to record a conversation to which you are not a party, do not have consent to tape, and could not naturally overhear.
Federal law and most state laws also make it illegal to disclose the contents of an illegally intercepted call or communication.
source: http://www.rcfp.org/taping/
Dave
It would just be better to let them know your going to record the conversation just like the let you know that they may record this conversation for quality assurance. Tell them the same thing.